工作这么久，虽然以前也安装过cocoapods，但是自己没有整理，最近有时间重新安装一次，顺便整理下。首先检查Ruby当前版本：
gem sources -
成功后提示：
*** CURRENT SOURCES ***
https://rubygems.org／
替换成国内的源：先要remove当前的ruby： gem sources --remove https://rubygems.org/
先前我们都是添加淘宝的镜像，但是在mac 10.12 系统上面会报错，ERROR: While executing gem ... (OpenSSL::SSL::SSLError)
hostname "upyun.gems.ruby-china.org" does not match the server certificate
这个不能替换成淘宝的，执行下面命令:gem sources -a https://gems.ruby-china.org/
执行下面命令:ruby -v 查看当前版本是否需要升级，ruby需要版本2.0以上，如果小于2.0 则需要升级系统的ruby版本。
执行：rvm list known 如果提示command not found 则运行：curl -L get.rvm.io | bash -s stable
如果提示
# ponted,
#
# Thank you for using RVM!
# We sincerely hope that RVM helps to make your life easier and more enjoyable!!!
#
# ~Wayne, Michal & team.
In case of problems: https://rvm.io/help and https://twitter.com/rvm_io
Upgrade Notes:
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代表安装成功
执行：rvm install 2.2.2 安装rvm 里面会直接帮你安装 Downloading and installing Homebrew...
之后就开始安装cocoapods：sudo gem install cocoapods
Done installing documentation for i18n, thread_safe, tzinfo, activesupport, claide, fuzzy_match, nap, cocoapods-core, cocoapods-deintegrate, cocoapods-downloader, cocoapods-plugins, cocoapods-search, cocoapods-stats, netrc, cocoapods-trunk, cocoapods-try, colored2, escape, fourflusher, gh_inspector, molinillo, ruby-macho, CFPropertyList, nanaimo, xcodeproj, cocoapods after 17 seconds
26 gems installed
提示安装成功.
